Pennsylvania State health officials first learned of a potential HAV outbreak from emergency room doctors in Beaver County, who reported an unusually high number of hepatitis A cases in late October, 2003. Investigators from the health department began investigating the people who had fallen ill, and determined that the common thread for all was having eaten at the Chi-Chi’s restaurant at the Beaver Valley Mall. Once the department isolated the restaurant as the probable source of the outbreak, Chi-Chi’s closed the restaurant voluntarily and it remained closed for a number of weeks.
Ultimately, over 650 confirmed cases, both primary and secondary, were linked to this outbreak. The victims included at least 13 employees of the Chi-Chi’s restaurant, and numerous residents of six other states. Three persons died as a consequence of their hepatitis A illness. In addition, more than 9,000 persons who had eaten at the restaurant during the period of potential exposure, or who had been exposed to ill persons, obtained immune globulin shots as protection against the hepatitis A virus.

The Pennsylvania Department of Health and the federal Centers for Disease Control and Prevention (CDC), along with the U.S. Food and Drug Administration (FDA), conducted further studies investigating the incident. Preliminary analysis of a case-control study indicated green onions were the probable source of this outbreak.
The green onions were typically shipped to the restaurant in boxes, and stored and refrigerated in a bucket of ice. They were eventually chopped up, and utilized in food served at the restaurant, often uncooked, as in the preparation of the mild salsa. “Preliminary trace-back information indicated that the green onions supplied to Chi-Chi’s had been grown in Mexico.”
An increasing proportion of reported foodborne outbreaks have been linked to fresh produce. Previous hepatitis A outbreaks have been linked to green onions, and have involved patrons of a single restaurant. The FDA issued a statement dated December 9, 2003, reaffirming that this outbreak, as well as others recently, was associated with eating raw or undercooked green onions. The investigation and trace-backs by the state health department, the CDC, and the FDA, confirmed that the source of the outbreak was green onions supplied to Chi-Chi’s.
Castellini began providing green onions to Chi-Chi’s on or about December 12, 2002. The green onions used in food sold to customers at the Chi-Chi’s in the Beaver County Mall in September and October, 2003 were sold by Castellini, through, Sysco to Chi-Chi’s pursuant to pre-existing agreements between Castellini and Chi-Chi’s. Part of the agreement with Chi-Chi’s included General Requirements for Chi-Chi’s suppliers, as well as a warranty on the product. Invoices from the Chi-Chi’s restaurant show Castellini as the sole supplier of green onions to the restaurant in the relevant time frame.